1. Field of the Invention
The present invention relates intermediate-level devices in networks involving multiple data reads over time, including but not limited to sensor networks and RFID networks. More particularly, the invention relates to middleware servers in RFID networks.
2. Description of the Related Art
“Smart labels,” generally implemented by RFID tags, have been developed in an effort to address the shortcomings of bar codes and add greater functionality. RFID tags have been used to keep track of items such as airline baggage, items of clothing in a retail environment, cows and highway tolls. As shown in FIG. 1, an RFID tag 100 includes microprocessor 105 and antenna 110. In this example, RFID tag 100 is powered by a magnetic field 145 generated by an RFID reader 125. The tag's antenna 110 picks up the magnetic signal 145. RFID tag 100 modulates the signal 145 according to information coded in the tag and transmits the modulated signal 155 to the RFID reader 125.
Most RFID tags use one of the Electronic Product Code (“EPC” or “ePC”) formats for encoding information. EPC codes may be formed in various lengths (common formats are 64, 96 and 96+ bits) and have various types of defined fields, which allow for identification of, e.g., individual products as well as associated information. These formats are defined in various documents in the public domain. One such document is EPC Tag Data Standards Version 1.1 Rev1.24 (EPCglobal® 2004), which is hereby incorporated by reference for all purposes.
One exemplary RFID tag format is shown in FIG. 1. Here, EPC 120 includes header 130, EPC Manager field 140, Object class field 150 and serial number field 160. EPC Manager field 140 contains manufacturer information. Object class field 150 includes a product's stock-keeping unit (“SKU”) number. Serial number field 160 is a 40-bit field that can uniquely identify the specific instance of an individual product i.e., not just a make or model, but also down to a specific “serial number” of a make and model.
In theory, RFID tags and associated RFID devices (such as RFID readers and printers) could form part of a network for tracking a product (or a group of products) and its history. However, various difficulties have prevented this theory from being realized. One problem that has required considerable time and energy from RF engineers is the development of lower-cost RFID tags with acceptable performance levels. RFID devices have only recently been deployed with network interfaces.
In part because of the significant efforts that have been expended in solving the foregoing problems, prior art systems and methods for networking RFID devices are rather primitive. Many uncertainties remain regarding the functionality and implementation of RFID networks. Although EPCglobal has emerged as a de facto standards body, data standards are still evolving and form factors for many solutions are unclear.
However, some general outlines of a solution appear to be taking shape. It is envisioned that a single facility (e.g., a warehouse, factory, retail outlet, etc.) may have a large number of RFID readers. Such RFID readers may be installed on or near shipping/receiving dock doors, forklifts, shelves, etc. Each RFID reader may transmit a large number of “reads,” many of which will be redundant. Due to the nature of the data gathering and sharing process, a hierarchy of middleware, edge servers/event processing engines and information services are likely to be deployed for all large RFID networks. “The EPCglobal Architecture Framework” (EPCglobal Final Version of 1 Jul. 2005) is hereby incorporated by reference for all purposes.
Accordingly, it is generally agreed that it would be desirable for most RFID networks to use “middleware” to perform functions such as data collection, filtering, aggregation and reporting of tag reads from physical RFID readers to higher-level applications. It would appear to be generally desirable that filtering and processing of information (e.g., of RFID reads) should occur as close to the network edge as possible, for bandwidth optimization, manageability, security, etc. However, many RFID devices and related network devices are deployed in a hostile industrial environment (such as a warehouse or factory) by relatively unskilled “IT” personnel. RFID devices and related network devices may not perform well in such rugged environments. Moreover, existing RFID middleware servers generally provide low levels of data security (if any).
It would be desirable to address at least some of these shortcomings of the prior art.